Voltage regulator question

[bradp]

Anyone have an illustrated parts catalog handy?

I have a 1977 J 24-0348.  At some point I replaced a gill with a Concorde battery- but the voltage regulator (in the worst possible place under the glare shield) never got adjusted.  Therefore I’m probably chronically undercharging my Concorde at 13.2 volts under load.   The highest I see after start is 13.8 volts.  Should presumably be up adjusted to 14.25 or so for the winter months  

I’m assuming VRs of this vintage were all adjustable. 

Anyone have the part number handy and/or instructions on how to adjust the POT?  

Thanks 

Brad

[PT20J]

Check bus voltgage with an accurate digital multimeter before changing anything. 

[larrynimmo]

my 1981 24-1189 has voltage regulator mounted just above the copilots knees with immediate access to adjust the pots....I have never adjusted

[PT20J]

Mooney seems to have moved the VR around a lot over the years. My '78 J had it mounted on the cabin side of the firewall behind the circuit breaker panel -- I haven't found it in my '94 J yet, but I think  it's behind the center console. 

It was a long time ago when I had the VR out of the '78. It was an OECO and it went bad so I removed it and replaced the power transistors and set it to the correct voltage on the workbench. I don't remember if it would have been possible to get to the voltage adjustment without removing the unit. I do remember that it was really, really hard to get it in and out. 

[bradp]

Yeah mine is also behind the CB panel high on the firewall almost unreachable.  

I’ll  confirm bus voltage accurately. 

[ArtVandelay]

My 78J has it by the copilot’s knee FWIW. Funny it in the same year it was put in 2 different locations.


Tom

[OR75]

my J serial number is with a few digits of yours ... it had an OECO 20082 . I just replaced it with a Zef

I did not try to adjust the field but here is a picture that should help you: 

under those two plastic seals ... adjustments for OV on the right , Reg on the left

no idea how sensitive the Reg adjustment is and if clockwise will increase or decrease - but the procedure is in the M20J maintenance manual. 

  

 

[231LV]

Along these same lines, I have a question for the group; what voltage do you see (on a 14v system) prior to start up and does your voltage pop up to the charging rate (14.2v) instantly upon startup? In my case, I see 12.2v after the plane has been sitting on a battery minder at 4 amps but the voltage slowly climbs to 14.2v after I start the engine...usually takes 10-15 seconds all the while my Low Volts light is flashing on my annunciator panel. My mechanic has tried everything and we can't figure out why it won't pop up to a full charge immediately.

[ArtVandelay]

Smart regulators don’t, they slowly rise to reduce loads and voltage spikes. They usually require a certain RPM to start generating power and may need higher RPMs to get to maximum charging voltage. You need to measure voltage, at the battery before turning on the master to get its resting voltage. I think everything is working as designed.

 

 

Tom

 

[markejackson02]

2 hours ago, 231LV said:

Along these same lines, I have a question for the group; what voltage do you see (on a 14v system) prior to start up and does your voltage pop up to the charging rate (14.2v) instantly upon startup? In my case, I see 12.2v after the plane has been sitting on a battery minder at 4 amps but the voltage slowly climbs to 14.2v after I start the engine...usually takes 10-15 seconds all the while my Low Volts light is flashing on my annunciator panel. My mechanic has tried everything and we can't figure out why it won't pop up to a full charge immediately.

I have a 12V J model, usual 12.2 or so before the start.  After the start it needs to idle at 1200RPM for a little while so I see ~14v, at 800-1000RPM like 13.5 anything over 1500RPM 14.2V

[FloridaMan]

Disregard my last post. I got ahead of myself and didn't see you'd posted the same chart that I went and looked up.